Although the following discussion will relate specifically to problems involved with the handling of silicon wafers, there is no intent to limit the applicability of the invention to such wafers. It should be understood that devices which employ the present invention may be utilized to handle, move, etc., any delicate divice or structure which has a substantially flat surface, which surface need only be large enough to be gripped by the device.
In recent years, development of many products has moved very rapidly toward micro-technology, particularly in the field of electronics in which circuitry has become so reduced in size as to be literally indiscernable to the human eye without the aid of optical devices. In the development of this technology, printed circuitry has been imposed upon silicon wafers which must be handled, treated, etched, stored, and cut into discs or chips.
Such wafers are normally extremely thin and brittle and must be handled with extreme caution. Normally, the printed circuitry is positioned on one side of the wafer and extreme caution is necessary to prevent any marring, scratching, or contamination of the printed side of the wafer. Since the printing normally covers the full surface of the wafer, it is imperative that the printed side of the wafer not be touched, either by a hand which might contaminate it, or by any tool which could mar or scratch it.
In the past, a wide variety of tools have been developed to handle such wafers. For example, tweezers specifically designed for this purpose have been illustrated in U.S. Pat. Nos. 3,469,807; 3,665,790; and 3,741,602. While these tools can be successfully employed to handle a wafer, such success is extremely dependent upon the attention and caution of the worker handling the wafer. Since the wafer must be handled a number of times from its initial production through its ultimate use, the possibility of damage and total loss of a wafer increases accordingly, in spite of the designs of the prior art tools. This occurs because all of the prior art tools, such as tweezers, have one common feature: one prong of the tweezer must touch the printed surface of the wafer, causing that particular area of the wafer, at least, to be unusable. Similarly, since many of the tweezers are relatively hard and some have rather sharp jaws, there is an increased possibility of marring, scratching, or chipping the wafer.
Further, the prior art tools do not provide as positive a control and security in handling such wafers as is desirable in mass production techniques, unless highly paid, skilled technicians are employed to do the work.
In production, the wafers are treated in a variety of ways and, in some instances, are subjected to temperatures of as high as 500.degree. C. The wafers must be maintained in a dust-free environment without contamination by the operator or his tools. They are often stored in "boats" which are slotted plastic containers in which the wafers are often located within 1/16 of an inch from one another. In such storage, the wafers are normally vertically oriented and, by analogy, resemble 35 mm film slides in their method of storage. It is mandatory that the wafer be moved in and out of the boat and through all other production steps without touching, contaminating, or marring it or the adjacent wafers. Also, during some stages of wafer fabrication, the wafers must be placed, with the printed side up, on a flat surface such as a tray or table.
In the past, in all of these circumstances the wafer had to be picked up by a tweezer or other similar tool. Thus, the chance of damaging a wafer was directly proportionate to the number of times which it had to be handled.
Consequently, it has become imperative to provide a tool which can be employed to quickly and easily handle a delicate article, such as the silicon wafer, without damaging the article and without requiring a high degree of skill by the worker just to handle that article.